Introduction to Viruses: Living or Nonliving?
The unit will begin with a brief review of prokaryotic and eukaryotic cells. The students will recall what characteristics bacterial, plant, and animals cell have classifying them as living. The students will then be introduced to viruses. The students will be asked to list what they know about a virus. This class will compile a list of what they think a virus is, where they come from, and if they positively or negatively affect their bodies. I expect most students to reference their experience with a virus as something that caused them to be sick. I will also expect students to have had the experience of doctors not prescribing antibiotics for their viral infections. This will be highlighted as an important piece that will later be investigated in the unit. Students will then discuss the importance of viruses in human populations. The students will then take notes on the structure and function of viruses.
The students will then be shown various micrographs of viruses using websites and textbook graphics (see viral websites listed at the end of the unit). They will be asked to describe the structural characteristics of the viruses. The various shapes of the viruses will be highlighted and students will be asked to categorize the viruses just by their structure in small cooperative groups. Next, the students will be given notes on the major components of a virus (capsid, nucleic acid, enveloped) with an emphasis placed on DNA and RNA being the genetic material.
The students will then be asked to recall the distinction between the two types of nucleic acids, and review DNA replication, transcription and translation. Mutations will be highlighted in this review, as this will be a key point in discussing the difficulties of developing a vaccine for a virus that has a high mutation rate such as HIV. Students will be given background on how viruses lack the characteristics of a living thing and how they are obligate parasites. This will be a new vocabulary term and the students will discuss in groups what they know about parasites and then look up the definition of obligate and then come up with a definition of their own term and compare it with the textbook definition. The exercise is intended to show students how they can figure out the meanings of words based on their knowledge plus the help of a dictionary.
Students will then distinguish between a bacterium and a virus. The students will then be split into two groups. One group will classify viruses as living and have to defend their position using the characteristics of a living thing. The other group will classify viruses as non-living and have to defend their position using the same characteristics of a living thing. The purpose of this activity is to reveal how science is not set in stone and there will be gray areas concerning various concepts in science.
Viruses: The Parasitic Life Cycle
Next, the students will create a concept map that distinguishes an infectious disease from genetic disease. In this concept map we will focus on creating a list of the most common infectious diseases and then determine whether they are viral or bacterial in origin. The students will then be introduced as to how viruses are not composed of cells and how this is a key distinction when comparing bacterial infections to a viral infection. Students will be informed that bacterial infections produce toxins and other foreign material that causes disease in their hosts. However, viruses attack from within the cell. Once the virus has entered the cell, the virus will take over the cell's normal activities to produce viral particles. The viral particles eventually overtake the intracellular space and usually cause the cell membrane to break open releasing the accumulation of assembled viral particles that were being stored within intracellular (Tortora, 2002).
Viruses are very specific to the host cell they will infect. A plant virus will not be capable of infecting an animal cell due to the different surface proteins that each unique cell type contains. Students will compare how animal viruses and bacteriophages infect specifically animal cells and bacterial cells due to the need of specific surface receptors to attach to. Plant viruses will not be used due to time restraints and the theme focusing on viruses affecting human health. The students will review the critical features of the cell membrane (as the cell membrane should have been covered earlier in the year) and the import role surface receptors play in acting as gateways to pass through the cell membrane. In order to provide a visual aid to the concept of cells and viruses attaching to each other via surface receptors, I am going to uses strips of Velcro attached to various shaped objects (sphere, cube, triangle)
The first main art activity will take place with the students constructing cells with very unique cell membranes. Students will create three-dimensional "shoe box" (or any other three-dimensional medium of choice) cells that provide an interactive depiction of how viruses pass through cell membranes or gateways into the cell. Each student's "shoe box" cell will have receptors on the surface of the cell with a specific shape that the virus can lock into and pass the viral nucleic acid into the cell. The possible materials that I intend to use for this activity can be found under the materials section at the end of unit.
Once cell models are completed, the students will start the construction of a virus. They will choose from a virus from the various groups of viruses that are classified based on their capsid shape (helical, polyhedral, complex, and enveloped). Various mediums can be used to construct the viruses and I have provided a materials section at the end of the unit to give you ideas. The viruses constructed by the students will have surface receptors that match the students' cell membrane surface receptors. The students will be directed without knowing to choose viruses that will not be able to attach to the surface membranes on the cell membranes they constructed. Once the students have constructed their viruses they will have to solve the mystery of how the viruses are entering the cells they each constructed. The students will have to interact with each other and their classmates' cells and viruses to solve the mystery.
Student Developed Workshops on HPV
The start of this last section will start by using a stuffed animal that is covered in a powder that fluoresces under ultra violet light. The students will be given the powdered stuffed animal to pass around the room under the pretenses they are to observe it. After the stuffed animal has circulated around the room, the students will be told they all have just been exposed to a "fake virus" by touching the animal. The students will then examine themselves under an ultra violet lamp to see just how much virus or the viral load that was transmitted to them while observing the stuffed animal. Those students with the greatest viral load will be informed that they most likely would of gotten sick from the virus represented by the powder on their bodies. This activity serves to show students how quickly a virus can spread throughout a population and cause illness in the population.
The students will then start researching specially the type of virus that causes HPV, how it is transmitted, who in the population is most at risk, and what type of treatments exist in preventing and treating the disease. Students will also research the link between a viral infection and the chances of developing cervical cancer in females and genital cancer in both males and females. The students will then use their research to develop workshops for their peers, families, and communities, to share their research.
The student workshops will contain three parts. The first part of the workshop will be to simply provide information about what constitutes a viral infection and what HPV stands for. The second part of the workshop will entail the students providing the details of the symptoms of HPV and how it can be transmitted sexually and orally. Students will emphasize how extremely common HPV is in young, sexually active populations with the most common manifestation of an infection being genital warts. The students will discuss how HPV can cause cervical cancer in females and genital cancer in both males and females. The third part of the workshop will involve discussing how transmission of the virus can be reduced slightly through condom use, reduction in the number of sexual partners, pap smears for women, and through vaccinations. The students will end discussing the safety of the vaccine and who should receive the HPV vaccine.
The workshops developed by the students will be the closing activity that will serve as a summative assessment. All of the students' work throughout the unit will be showcased in these student-facilitated workshops that will be designed to educate their peers, families, and local community members on HPV. The students will be able pull the various parts of our journey through the unit to teach others their enriched knowledge concerning the topic of viruses and vaccines. The student-generated workshop provides an interdisciplinary approach to the unit with the students exercising their civic skills to strengthen their communities by putting their education into action.